NE-AUA 2006 Annual Meeting, September 28 - 30, 2006, The Westin Hotel & Rhode Island Convention Center Providence, Rhode Island
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Tamsulosin and Extended-Release Oxybutynin: Effects of Combination Therapy on Lower Urinary Tract Symptoms in Men
Victor W. Nitti, MD1, Andrew Chen, MS2, Nora Tu, PhD2, Joseph W. Aquilina, MD3, Scott A. MacDiarmid, MD4.
1New York University Medical College, New York, NY, USA, 2Ortho-McNeil Pharmaceutical, Raritan, NJ, USA, 3McNeil Consumer & Specialty Pharmaceuticals, Fort Washington, PA, USA, 4Wake Forest University School of Medicine, Winston-Salem, NC,

Background: We evaluated the efficacy and tolerability of extended-release (ER) oxybutynin in combination with the α1-blocker tamsulosin in reducing lower urinary tract symptoms (LUTS) in men.
Methods: In this multicenter, double-blind trial, men ≥45 yrs of age with a total International Prostate Symptom Score (I-PSS) ≥13 and an I-PSS storage score ≥8 were randomized to receive tamsulosin 0.4 mg/d with either ER oxybutynin 10 mg/d or placebo for 12 weeks. Subjects were required to demonstrate a maximum flow rate ≥8 mL/sec with voided volume ≥125 mL and a post-void residual (PVR) volume ≤150 mL on 2 occasions in order to qualify. PVR volume and peak flow rates (PFR) at weeks 4, 8, and 12 were measured. The primary endpoint was change from baseline in total I-PSS after 12 weeks of treatment. Effects on I-PSS storage and I-PSS quality of life (QoL) scores were analyzed; symptom bother was further evaluated using the Symptom Problem Index (SPI).
Results: A total of 418 men were randomized and took drug. Tamsulosin combined with ER oxybutynin resulted in a significantly greater improvement in total I-PSS compared with tamsulosin and placebo after 8 (P = 0.033) and 12 (P =0.006) weeks of treatment. Combining active treatments resulted in greater decreases in I-PSS storage scores after 4 (P = 0.008), 8 (P < 0.001), and 12 (P < 0.001) weeks of therapy. Greater improvements in QoL scores were also observed (P = 0.006, wk 4; P < 0.001, wk 8; P = 0.001, wk 12). Improvement in symptom bother as indexed by the SPI was significantly greater with combination therapy at weeks 8 (P = 0.017) and 12 (P = 0.037). The incidence of elevated PVR volume (>300 mL) was 2.9% (n = 6) in patients on combination therapy and 0.5% (n = 1) in patients on tamsulosin alone (P = 0.122). No patient in either group experienced acute urinary retention. Incidence of reduced PFR (<5 mL/sec) was 3.8% (n = 8) and 5.7% (n = 12), respectively (P = 0.493). Adverse events leading to discontinuation occurred with similar frequency in the 2 groups (10.0% and 9.6%, respectively).
Conclusions: In men with significant storage LUTS, combination therapy with tamsulosin and ER oxybutynin demonstrated greater efficacy than tamsulosin monotherapy, with comparable safety and tolerability.


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